Promoted porous catalyst

ABSTRACT

A novel precious metal doped porous metal catalyst is disclosed. The precious metal is present in from 0.01 to 1.5 weight percent and distributed throughout the particles of porous metal to provide a surface to bulk ratio distribution of not greater than 60. The present invention is further directed to a process of forming said doped catalyst and to improved processes of catalytic hydrogenation of organic compounds.

BACKGROUND OF THE INVENTION

The present invention is directed to a new catalyst product and to aprocess of reducing organic compounds using said product. Morespecifically, the present invention is directed to porous base metalcatalyst product having at least one precious transition metal dopantdistributed on the surface area of the catalyst such that the surface tobulk ratio of dopant has a distinctly low value, as fully describedherein below. The present doped catalyst product has been found toexhibit high catalytic activity and extended catalytic life compared topreviously achieved values.

Hydrogenation catalysts based on highly porous nickel materials are wellknown. Such materials are part of a family of metal alloy derivedproducts sold by W. R. Grace & Co.-Conn. under the trademark “Raney®”.These porous materials, when microscopically viewed, take on asponge-like appearance having tortuous pore channels throughout thenickel metal particle. Thus, such materials are generically viewed asporous or spongy metal alloy products. The metal alloy is generallycomposed of a major amount of a base metal selected from nickel, cobaltor copper with minor amounts of aluminum and other metals such as iron,chromium or molybdenum, as deemed appropriate for a particularapplication. The porous base metal catalyst product is normally referredto in terms of the metal which is the major component of the spongymetal product. These high surface area products have been found to havesites for hydrogen activation and, thus, exhibit catalytic activity whenused in hydrogen reduction reactions.

It is known that the activity of spongy base metal catalysts can beenhanced (“promoted”) by the incorporation of small amounts of certaintransition metals. For example, French Patent 913,997 proposedincorporating chromium in up to 3.5 percent based on the content ofnickel present in a Raney nickel catalyst. Promotion of catalysts wasinitially accomplished using transition metal elements which are readilyavailable commodity metals, such as iron, molybdenum or chromium. Thesemetals could be used in large amounts without causing a detrimentaleconomic limitation to their commercial usefulness.

In general, porous base metal catalysts, such as porous nickel catalystsare formed by first producing a base metal-aluminum (preferred) or basemetal-silicon alloy using conventional metallurgical techniques. Theformed alloy is ground into a fine powder and classified by passing itthrough a sieve to provide a material having a desired particle sizewhich is normally less than 500 microns and, preferably less than 75microns. Larger particles are recycled for further grinding.

The alloy powder is then treated with a base to leach out a substantialamount of the aluminum metal or silica present. The base may be selectedfrom either an inorganic (preferred) or organic compound. For example,in conventional processes an aqueous solution having from about 5 to 50weight percent concentration of an alkali metal hydroxide (e.g., sodiumhydroxide) is employed as the leaching agent. The treatment of the alloyis usually carried out at elevated temperatures of from about 40° C. to110° C. The alloy powder can be directly added to the alkali solution orit can be formed into an aqueous suspension which is then contacted withthe alkali solution. The aluminum contained in the alloy dissolves toform an alkali metal aluminate (e.g., sodium aluminate) with vigorousevolution of hydrogen. When silicon is in the alloy, the base forms thecorresponding alkali metal silicate. The powder and alkali are normallyallowed to remain in contact with each other for several hours atelevated temperature (e.g., 40°-110° C.) until the aluminum (or silicon)content is reduced to the desired level. The crude porous catalyst isseparated from the reaction liquor and then conventionally washed withwater until the wash water has a slightly alkaline pH value of about 8.The pore volume, pore size and surface area of the leached alloy willdepend upon the amount of aluminum (or silicon) in the initial alloy andthe degree of leaching. The nature of the porosity of the resultant basemetal catalyst is one of tortuous pores throughout the volume of thecatalyst particle. The resultant product normally has a pore volume(BET) of from about 0.05 to about 0.3 cc/g; an average pore diameterranging from about 50 to 500 Angstroms; and a surface area (BET) of atleast 10 m²/g, preferably ranging from about 20 to about 150 m²/g.

The resultant porous base metal product has been used as a hydrogenationcatalyst to cause reduction of organic compounds, such as, for example,nitroorganics, to their corresponding amine compound. In order tofurther enhance the catalytic properties of such porous products, theaddition of promoter metals, such as Group VIII transition metals (e.g.,iron or chromium), has been previously accomplished by (i) adding thepromoter metal to the base metal and aluminum (or silicon) whenmetallurgically producing the initial alloy; (ii) adding a salt of thepromoter metal to the alkali leaching solution; or (iii) contacting theleached or leached and washed porous base metal catalyst with a saltsolution of the promoter metal.

The process of adding promoter metal to the base metal during alloyformation, as disclosed in U.S. Pat. No. 3,781,227, has certainlimitations. Firstly, it can be envisioned that some of the promotermetal is “encapsulated” in the solid body or skeleton of the base metaland not on the surface area of the resultant catalyst. In this form, thepromoter metal does not cause a direct enhancement of the hydrogenationcatalyst sites which are located on the surface area of the highlyporous material. Further, a portion of the promoter metal may be removedduring any one or all of the steps required to form the porous alloy.Thus, large amounts of a promoter metal are normally added during alloyformation to compensate for any loss during processing and throughencapsulation. Because of the possible loss of promoter metal duringprocessing and the inefficiency of encapsulated promoter metal, thealloy-addition method is not considered appropriate when the metal is acostly transition metal, such as platinum, palladium, osmium, rutheniumor the like.

Alternately, promoter metals have been added to the alkali leachingsolution (see Great Britain Patent 1,119,512 and U.S. Pat. No.3,326,725) in attempts to enhance resultant porous nickel's catalyticactivity. The leaching solution is normally an alkaline aqueous oraqueous-alcoholic solution. In general, the promoter metal is introducedas an acid salt, such as a halide salt. In most instances, the leachsolution does not maintain the promoter metal in solution but, instead,causes it to plate out on the outer shell of the porous base metalparticle. Thus, the resultant porous particle has the promoter metallocated on only a small fraction of the particle's surface area.

Spongy nickel or other base metal catalysts which have been previouslyformed and washed by conventional processes have been subjected todopant metals just prior to use, in attempts to promote its catalyticactivity. The dopant metal is normally introduced as an aqueous oraqueous/alcoholic solution of an acid salt, such as PtCl₄, PdCl₂,H₂PtCl₆ or the like. In JACS 71 1515 (1949) and JACS 72 1190 (1950)Levering et al. disclosed the addition of an organic tertiary amine tothe acid salt dopant solution. These authors taught that one should usethe doped spongy metal product immediately after the addition of dopant(without further washing), in order to achieve enhanced catalyticperformance. Such products exhibited only slight increase in catalystactivity and substantially no improvement in their active catalyst life.

It is highly desired to provide a promoted porous base metal catalyst(e.g., Raney® nickel) which exhibits high catalytic activity afterstorage (maintains good initial activity) and extended catalyst lifeduring use (exhibits slow or delayed deactivation). Further, it isdesired to provide a promoted base metal catalyst which has a precioustransition metal as its promoter metal and said precious transitionmetal is substantially uniformly distributed as a coating on the surfacearea of the porous metal catalyst. Thus, the precious transition metalis substantially uniformly distributed across the particle diameter ofsaid catalyst. Still further, it is desired to provide a precioustransition metal promoted porous base metal catalyst wherein saidpromoter metal is present in up to about 1.5 percent by weight and thepromoter metal's surface to bulk ratio (as defined herein beiow) is lessthan 60.

SUMMARY OF THE INVENTION

The present invention provides a novel transition metal promoted porousbase metal catalyst. The transition metal is present in from 0.01 toabout 1.5 percent by weight, and is distributed throughout the surfacearea of said porous catalyst so as to have a surface to bulkdistribution of not greater than 60. The present invention furtherprovides a novel method of forming said precious transition metalpromoted porous base metal catalyst. Finally, the present inventionprovides an improved process for hydrogenation of organic compoundsutilizing said catalyst.

DETAILED DESCRIPTION

The following defined terms are used in this specification and appendedclaims:

“Base metal” refers to metals of iron, nickel, cobalt, copper andmixtures thereof which are used to form porous or spongy metal catalystproducts. These metals may be combined (e.g., alloyed) with minoramounts of other metals (e.g., chromium, titanium, molybdenum, zinc,zirconium, aluminum) as an alloy or co-deposited coating. When more thanone base metal is present in the spongy metal catalyst, all of said basemetals shall be included in determining the S/B ratio, as defined below.The preferred base metals are nickel and cobalt and most preferablycomprises nickel alone or with minor amounts of other metals.

“Precious metal” refers herein to transition metals of palladium,platinum, ruthenium, rhodium, rhenium, osmium, iridium and mixturesthereof.

“Dopant metal” refers to a transition metal which is distinct from themetals forming a porous base metal catalyst and is present in lowconcentrations in the base metal catalyst to enhance its catalyticproperties (e.g., dopant precious metals, as defined below, and may alsoinclude chromium, molybdenum, titanium, zinc, iron, zironium or mixturesthereof).

“Dopant precious metal” and “promoter precious metal” each refers hereinto precious transition metals of Pd, Pt, Ru, Re, Rh, Ir and Os presentin small quantities on the surface area of a porous, particulate basemetal for the purpose of enhancing the catalytic properties of saidporous, particulate base metal. The preferred dopant transition metalsare those of platinum and palladium with palladium being most preferred.

“Surface volume” refers to the outer volume or shell of a catalystparticle of the present invention which is roughly the outer 50Angstroms of the particle's radius (i.e., extending from the outersurface of the particle inward toward the center of the particle byabout 50 Angstroms).

“Surface dopant concentration” refers to the atomic ratio of dopantmetal to base metal within the surface volume of a catalyst particle.

“Bulk dopant concentration” refers to the atomic ratio of dopant metalto base metal for the entire catalyst particle.

“Surface to Bulk Ratio” or “S/B” in respect to a porous base metalcatalyst product, refers to ratio of surface dopant concentration tobulk dopant concentration.

The present invention is directed to a novel hydrogenation catalystproduct based on a porous base metal catalyst which has up to about 1.5weight percent of a precious transition metal selected from palladium,platinum, rhodium, ruthenium, rhenium, iridium or osmium or mixturesthereof coated on the surface area of said catalyst and having saidprecious transition metal of sufficiently low concentration in theparticle's surface volume to provide a surface to bulk ratio, S/B, ofless than 60. The present catalyst is particularly useful in reducingnitroaromatics to their respective amine derivatives.

The present catalyst is based on porous, particulate base metal catalystproduct, preferably a nickel metal (e.g., Raney® nickel) product. Thepresent invention shall be described by using a porous, particulate basemetal product wherein the base metal is composed of nickel. It is to beunderstood that other porous, particulate base metal products (Co, Cu,Fe) can be substituted and used to form the present improved catalystand the process of hydrogenation using the same.

The porous base metal (e.g., nickel) catalyst product is formed byconventional techniques. For example, a nickel/aluminum alloy isinitially formed by a pyrometallurgical process to provide an alloyhaving from about 30 to 60 (preferably from about 42 to 56) weightpercent nickel and from about 70 to 40 (preferably from about 58 to 44)weight percent aluminum. Small amounts of other base metals may,optionally, be present. The alloy is crushed and ground into particleshaving an average particle size of less than 500 micron diameter,preferably less than 75 micron diameter. The powder product is activatedby leaching the aluminum from the alloy with an alkali solution, such asan aqueous solution of sodium hydroxide (preferred) or potassiumhydroxide. The alkali is used at concentrations of greater than about 15weight percent, preferably from 15 to 35 and most preferably from 20 to35 weight percent. The leaching can be carried out at ambienttemperature but preferably is conducted at elevated temperatures whichcan be as high as the boiling point of the leaching solution.Temperatures of from about 40° to 110° C. (preferably 60° C. to 100° C.)are suitable to cause substantial rate of leaching and removal of thealuminum metal from the alloy. When the present catalyst is contemplatedfor use in fixed bed reactors, the porous, particulate base metalproduct may have an average particle size diameter (or largestdimension) of from about 0.1 to 0.8 cm. The alloy is leached with analkali solution described above having an alkali concentration of fromabout 5 to 35 weight percent, preferably from about 5 to 20 weightpercent. The leaching is normally carried out at elevated temperaturesof from about 30° C. to about 90° C., preferably from about 300 to 50°C.

The resultant porous particulate catalyst product is composed of basemetal, such as nickel and, optionally, minor amounts (up to about 15 wt.percent preferably up to about 12 wt. percent) of other transitionmetals as well as residual aluminum. It is to be understood that theterm “base metal” and the like used to described and define the spongymetal catalyst herein and in the appended claims shall mean (unlessspecifically stated otherwise) a metal product composed of a majoramount (at least about 85 wt. percent) of a single base metal or amixture of base metals (normally one base metal is in majority) whichhas a minor amount (up to about 15 wt. percent, preferably up to about12 wt. percent) of other metal(s) such as chromium, titanium,molybdenum, zinc, zirconium or mixtures thereof as well as with residualaluminum. The product has a high degree of tortuous pores throughouteach of the particles to provide a high surface area porous particulatecatalyst product. This product is washed with water to remove thealuminate by-product. Total removal of the aluminate is not required.The washing is conducted with water having a temperature of from ambientto about 60° C., preferably between 30 and 45° C. It is preferred thatthe washing be conducted under an inert (e.g., N₂ or Ar) atmosphere orone having a dilute concentration (2-8%, preferably 3-5%) of hydrogen.The resultant particulate product normally has a pore volume(Nitrogen-BET) of from about 0.05 to about 0.3 cc/g; an average porediameter ranging from about 50 to 500 Angstroms; a surface area (BET) ofat least 10 m²/g and preferably ranging from about 20 to about 150 m²/g;and an average particle diameter of less than 500 microns preferably ofless than 75 microns or, when contemplated for use in fixed bedreactors, of from about 0.1 to 0.8 cm.

In the instant invention washing is continued until the effluent washwater has an alkaline pH of from at least 8 to about 12 with from 9 to12 being preferred and from 10 to 11.5 being most preferred. Thealkalinity of the aqueous slurry containing the porous base metalcatalyst may be substantially the same as the alkalinity of the dopantprecious metal solution to be used to from a doped catalyst, asdescribed herein below.

The porous base metal catalyst is treated with an alkaline solution of abasic salt of the dopant precious metal to provide the catalyst of thepresent invention. The salts found useful in providing the uniquecatalyst are alkaline salts represented by the general formula(A)_(x)MY_(y) wherein A represents a cation or ligand selected fromammonia, ammonium, or an alkali metal such as sodium, potassium or thelike or mixtures thereof; M represents a precious transition metal, asdefined below; Y represents an anion selected from halide, hydroxide,oxide, carbonate, bicarbonate, nitrate, sulfate or a C₁-C₄ carboxylate;and x and y represent integers of from 1 to about 6 to provide a neutral(charge balanced) salt product. A is preferably selected from ammonia orammonium and most preferably selected from ammonia or if A is an alkalimetal it is preferably selected from sodium. The salt should be solublein water or alcohol or mixtures thereof and cause the solution toexhibit an alkaline pH of from 8 to 12, preferably from 9 to 11.5 andmost preferably from 9.5 to 11.5. Examples of such salts are:(NH₃)₄PdCl₂.nH₂O, (NH₃)₄PtCl₂.nH₂O(NH₃)₄Pd(NO₃)₂.nH₂O,(NH₃)₄Pt(NO₃)₂.H₂O, [Pt(NH₃)₄][PtCl₄], (NH₃)₆RuCl₃, NH₄ReO₄, (NH₃)₄ReO₄,KReO₄, NaReO₄, [Rh(NH₃)₅Cl]Cl₂, (NH₃)₄PtCl₂, K₂OsO₄.nH₂O, and the like.The symbol “n” can be an integer of 0 to 4.

The precious transition metal (M) of the basic salt is selected from Pd,Pt, Ru, Rh, Re, Ir and Os and mixtures thereof with Pd and Pt beingpreferred and Pd being most preferred. It has been found that thepresently described precious transition metals provide high catalyticactivity and extended catalytic life when plated in very low amounts onthe surface area of a porous base metal particulate material accordingto the present invention.

The porous, particulate base metal catalyst is doped with the precioustransition metal according to the present invention by contacting analkaline slurry of the porous base metal material with an alkalinesolution of a precious metal salt. Alternately, one can add the solidsalt directly to the affected slurry whereupon it dissolves to form thecombined alkaline solution and slurry. The salt should be used in anamount such that the weight concentration of dopant transition metal inthe resultant doped catalyst is from 0.01 to 1.5%, preferably from 0.05to 1% and most preferably from 0 to 0.5% by weight based on the weightof the porous base metal catalyst. The exact amount of salt used willdepend on the degree of doping desired in the finished catalyst.Normally, the alkaline salt should be added to water or water-alcohol toprovide a solution of salt wherein the salt concentration is from about5 to 40 (preferably 10-30) weight percent.

The porous base metal catalyst may, in addition to the precioustransition metal dopant, be doped with a non-precious metal dopantselected from iron, chromium, molybdenum, titanium, zinc, vanadium,zirconium or mixtures thereof. They may reside as a coating on thesurface in the form of a dopant metal in its zero valence state or in anoxidized state. These dopant metals may be present in up to 3 weightpercent (preferably from 0.2 to 3 weight percent, most preferably from0.5 to 2 weight percent) of dopant metal based on the weight of theporous base metal catalyst. They are added by conventional processesusing dopant metal salt solutions. The doped base metal catalyst mustalso be doped with a dopant precious metal, as described herein.

The alkaline precious metal salt solution is contacted with an aqueousslurry of the powder porous base metal catalyst, previously formed asdescribed above, for a sufficient time to allow substantially completeplating out of the precious transition metal onto the surface area ofthe base metal catalyst. The exact length of time will depend on theparticle size, and specific porosity of base metal used, the pH of thesolution and the concentration and particular precious transition metalpresent. Normally, the porous base metal catalyst and the alkalineprecious transition metal salt are maintained in contact in the slurryfor an extended period of time such as from about 10 to 60 minutes orlonger with from about 15 to 45 minutes being preferred. The temperatureat which this is conducted is not critical and can be, for example fromroom temperature to about 80° C. such as from 30-45° C.

The spent solution is then separated from the doped catalyst. The dopedcatalyst must then be washed until the wash solution is free of precioustransition metal. The wash solution should be an aqueous solution(preferred) or an aqueous-alcoholic (C₁-C₃ alkanol) solution. During thewashing a majority of by-product salts (e.g., NH₄Cl, NaCl) are removed.The washing should continue until the solution containing the dopedcatalyst has a pH of at least 0.25, preferably at least 0.5 and mostpreferably at least 1 (e.g., 1.5), unit lower than the alkaline pH atwhich the porous base metal catalyst and the alkaline precioustransition metal dopant salt are contacted. The pH can be reduced bywashing the doped catalyst with water or water-alcohol solutions(preferred) and/or by the addition of an acidic agent or a buffer agentto cause the resultant slurry to have the desired pH. It is preferredthat the aqueous suspension of doped catalyst resulting from thewashing(s) have a resultant pH of from about 8 to 9.5, preferably 8 to9. It is preferred that the pH of the doping slurry be high (e.g.,9.5-12) and that the aqueous slurry of doped catalyst is at least 1 unitlower after washing. When the base metal catalyst and precioustransition metal dopant are contacted in an alkaline slurry having a pHof 8 to 9.5, the product should be washed with at least 25 parts (e.g.,from 25 to 100 parts) of water for each part by weight of doped catalystsolid. The wash water may be of neutral pH or slightly alkaline by theaddition of a base such as NH₄OH, NaOH or the like. The washing can beoptionally followed by an alcohol (C₁-C₃ alkanol) or water-alcohol wash.The resultant doped base metal catalyst is normally stored as an aqueousslurry until use.

In addition to washing, or in lieu thereof, the doped catalyst can beremoved from the spent dopant solution and soaked in water or an aqueousalcoholic (C₁-C₃ alkanol) bath for at least 12 hours, preferably atleast one day prior to use. This aging has been found to aid inachieving a highly desired catalyst of low S/B ratio.

It has been found that the doped catalyst product formed in the mannerdescribed above can be stored for an extended period of time of from oneday to six months or greater prior to use without losing its catalystactivity. In addition, the doped catalyst product formed in the mannerdescribed above exhibits extended catalytic active life during use whencompared to conventional catalyst products of the same material.

It is believed, though not meant to be a limitation on the subjectinvention, that solutions of the present precious transition metal saltsare capable of penetrating into the pores of the base metal catalystwherein precious metal electrochemically plates out when reduced by thebase metal itself and/or by a fraction of the surface hydrogen of thebase metal material. In addition, it has been found that beyond theremoval of undeposited species, the final washing and/or soaking of theprecious transition metal doped porous base metal catalyst also aids inproviding a more homogeneous or even distribution of precious transitionmetal throughout the surface area of the product. The immediate useafter addition of the dopant salt does not allow the full migration ofthe dopant to the interior of the particles, while the present moretime-extended process completes this migration to a final, more stableconfiguration. Removal of undeposited species by washing also makes fora chemically enhanced product which is more compatible with a variety ofhydrogenation processes and has been shown in some processes to lead tosuperior activity.

As stated previously, the doped catalyst of the present invention is ahighly porous particulate product in which the pores are of a tortuousnature throughout each of the particles to provide a high surface areadoped catalyst product. The surface area as used herein and in theappended claims is all areas assessable to nitrogen and measured by theNitrogen-BET method. The term “surface” as used herein and in theappended claims shall be surfaces of the tortuous pores throughout saidparticles and of the particles, per se.

The presently produced precious transition metal doped porous base metalcatalyst has been found to have a more homogeneous or even distributionof precious transition metal throughout the surface area of eachparticle of the porous base metal catalyst. This can be described interms of the atomic ratio of the precious transition metal to base metalas a function of the cross-section of the catalyst particles. Thisdistribution can be readily measured by x-ray photoelectron spectroscopy(“XPS”) or electron spectroscopy for chemical analysis (“ESCA”). Anothertechnique to determine the atomic ratio of the metals is transmissionelectron microscopy (“TEM”). ESCA analytical method simultaneouslymeasures the outer surface volume or skin to a depth of about 50 Å of alarge number of particles. Thus, an atomic ratio of dopant metal tobasic metal in the surface volume of the particles can be measured andwhen compared to the bulk chemical analysis one can determine the amountof dopant enhancement at the surface versus the overall amount ofdopant. It has been found that with respect to the present dopedcatalysts, the amount of dopant enhancement in the surface volume is lowand thus the amount of dopant metal residing in the internal volume(between about 50 Å to the center of a particle) is proportionatelyhigher than that of known doped porous catalysts. Prior known dopedcatalysts are products where the dopant metal is very highlyconcentrated in the outer surface volume and, conversely, the dopantmetal is in a very low concentration in its internal volume.

The ratio of surface concentration to bulk concentration of the dopantprecious metal (referred to herein after and in the appended claims as“S/B ratio”) can be readily determined by ESCA analysis and bulkanalysis of a product. The S/B ratio of the precious transition metaldoped base metal catalyst of the present invention is less than about60, with S/B ratios of about 10 to 50, preferably 10 to 40 beingattainable. All ratios within this range of 10 to 60 being encompassedherein by this statement. In contrast, porous base-metal catalystsconventionally doped with equivalent amounts of precious metal have S/Bratios which are a multiple factor higher. Thus, if one were to plot aconcentration of precious transition metal across the particle diameter,one would obtain a curve less steeply peaked at the edges (outer 50 Å)for the presently doped catalyst product than for conventionally formedcatalyst product having the same degree of dopant precious metal.

The subject doped catalyst, especially the preferred doped nickelcatalyst, has been found to exhibit improved catalytic activity of fromabout 1.2-1.8× greater than the conventional doped catalyst and overconventional doped base metal derived alloy catalysts as shown bycomparative examples herein below.

The doped catalyst product of the present invention can be described asa porous, base-metal catalyst material. It is composed of a major amount(up to about 85 wt %) of a base metal, e.g. Ni, Co, Cu, or Fe, and minoramounts of up to about 15 wt. percent, preferably up to about 12 wt.percent of other metals (than the major base metal) selected fromaluminum, chromium, iron, copper, molybdenum, tin, zirconium, zinc,titanium, vanadium or mixtures thereof. The porous base metal catalysthas a precious metal dopant selected from Pt, Pd, Ru, Rh, Re, Ir, Os ormixtures thereof in up to about 1.5 wt. percent (e.g., 0.01 to 1.5),preferably from 0.05 to 1, such as 0.1 to 0.9 and most preferably from0.1 to 0.5 wt. percent (and all ranges included within said range of0.05 to 1.5 wt. percent). The dopant precious transition metal is coatedon a portion of the surface area of said porous base metal and isdistributed within the particles with respect to their diameter so thatits S/B ratio is less than 60, such as from about 5 to about 60,preferably less than 50, more preferably less than 40 and mostpreferably less than 35. The lower the S/B ratio the more preferred isthe resultant catalyst.

The product of the present invention is formed by the process ofcontacting a solution of an alkaline salt of the precious transitionmetal which may be described by the formula A_(x)MY_(Y) wherein each ofthe symbols A, M, Y, x and y are defined above, with an alkaline slurryof a porous base metal catalyst. The slurry, at a pH of from 8 to 12,preferably from about 9 to 11.5, is contacted with an alkaline saltsolution, as described above, for a period of time to allowsubstantially all of the precious transition metal of the salt to becomecoated on and adhered to portions of the surface area of said porousbase metal catalyst. The product of said contact is then washed untilthe wash solution is essentially free of dopant metal and has a pH whichis at least 0.25 unit lower than the pH of the doping slurry.Alternately or in addition to the pH adjustment (preferable) the washingis conducted with at least 25 wt. parts of water for each wt. part ofsolid product. The doped base metal catalyst of the present invention isaged in an aqueous or aqueous-alcoholic solution for at least 12 hourspreferably one day prior to use. The washed product is maintained in anaqueous or aqueous-alcoholic bath until use.

The doped catalyst product of the subject invention is useful as ahydrogenation catalyst. The present product has been found to have highcatalytic activity and provide extended catalytic life when compared toconventional porous base metal catalysts which have the same dopant. Thepresent doped catalyst products have S/B ratios which are substantiallylower (more uniform doping) than conventional products.

The present invention further provides for improved catalytichydrogenation reduction processes conducted in the presence of theabove-described doped catalyst. Said processes include all hydrogenationreactions which are carried out with porous base metal catalysts, suchas Raney® nickel catalysts. Examples of such reactions are described inSkeleton Catalysts in Organic Chemistry by B. M. Bogoslawski and S. S.Kaskowa and in Use of Nickel Skeleton Catalysts in Organic Chemistry VEBDeutsches Verlag der Wissenschaften, Berlin 1960 Pg. 40-124, theteachings of which are incorporated herein in their entirety byreference.

Accordingly, for example, the metal catalysts prepared according to theinvention can be employed for the hydrogenation of unsaturatedhydrocarbons with an ethylenic and/or triple bond, or of diene systems,of aromatic compounds, such as, for example, benzene, naphthalene,diphenyl and their derivatives, or of anthraquinone and phenanthrene, ofheterocyclic compounds with nitrogen, oxygen or sulfur atoms in the ringsystem, of carbonyl groups, of carboxyl groups or their esters, ofcarbon-nitrogen compounds, such as, for example, nitriles, acid amides,oximes and ketimines, of unsaturated compounds containing halogen,sulfur, nitroso and nitro groups, of azo and azoxy compounds, ofhydrazines, Schiff's bases, imines and amines, of carbon-oxygencompounds, such as, for example, alcohols, ethers, ethylene oxides andorganic peroxides and ozonides, of carbon-carbon compounds and ofnitrogen-nitrogen compounds.

The doped catalysts prepared according to the invention are preferablyused for the hydrogenation of nitroso and nitro derivatives of aromaticcompounds, unsaturated hydrocarbons, and nitriles. For example,nitrobenzene and nitrotoluene as well as dinitrobenzene anddinitrotoluene can be readily reduced to their corresponding primaryamine derivative by contacting the nitro aromatic compound with hydrogenin the presence of the doped catalyst of the present invention. Thereactions can be carried out at ambient temperature and pressure or atelevated temperatures of up to about 175° C., preferably between about60° C. and 150° C. The reactions can be carried out at pressures of upto about 1000 psig with preferred pressures being from about 100 toabout 500 psig. It has been unexpectedly found that the present dopedcatalyst provides very high degree of enhanced reactivity when usedunder elevated temperature and pressure conditions. Thus, conditions oftemperature of from about 130 to 175° C. and pressures of from 300 to500 psig are preferred. The use of the doped catalyst of the presentinvention is exemplified herein by illustration of hydrogenationreduction of para-nitrotoluene.

The hydrogenation may be carried out in a continuous sump phasehydrogenation apparatus, which consists of a number of reactors ofcustomary construction connected in series, with the aid of which ahydrogen cycle is produced. Other conventional batch and continuousapparatus may be used. The catalyst of the present invention can besuspended in an aqueous-alcoholic mixture (e.g., a C₁-C₃ alkanol).Alternately, the catalyst may be of a fixed bed type (larger particlesize of from about 0.1to 0.8 cm) used in a packed bed reactor witheither a liquid or vapor phase reaction mixture conventionally used.

The doped catalyst of the present invention can be suspended in thehydrogenation apparatus in an ethanol/water mixture, for example with amixture composed of 95% by weight of ethanol and 5% by weight of water,as the solvent. A solution of para-nitrotoluene in the ethanol/watermixture is formed and to it the catalyst is added. The treatment is thencarried out at elevated pressure, for example 60 to 500 psig of hydrogenpressure, and at temperatures of 75° C.-140° C.

The following examples are given for illustrative purposes only and arenot meant to be a limitation on the invention as defined by the claimsappended hereto. All parts and percentages are by weight unlessotherwise indicated. Further, any range of numbers recited in thespecification or claims, such as that representing a particular set ofproperties, conditions, physical states or percentages is intended toliterally incorporate expressly herein any number falling within suchrange, including any subset of numbers within any range so recited.

EXAMPLE I Preparation of Base Metal Catalyst

A previously formed nickel-aluminum alloy composed of about 42 weightpercent nickel/58 weight percent aluminum was ground into a powderhaving particle size of about 30-40 microns average diameter. Thepowdered alloy was intermittently added in small portions to a 30 weightpercent sodium hydroxide solution which was preheated to 80° C. prior tointroduction of alloy. The weight ratio of NaOH (solid) to Al of thealloy was about 2.7:1. The addition was carried out at a rate of about1000 g alloy powder per hour. After completion of the addition of alloypowder, the resultant slurry was maintained at 80° C. with agitation forabout 4 hours.

The resultant spongy nickel catalyst was separated from the slurryliquid by decantation followed by washing of the solid catalyst untilthe spent wash solution had a pH of about 9. The washing of the solidcatalyst was carried out by cyclic addition of water at 45° C. followedby stirring, settling of solids and decanting of the wash water.

The resultant spongy nickel metal catalyst was stored as a 50 wt.percent aqueous slurry.

EXAMPLE II Precious Metal Doped Nickel Catalyst

A series of nickel catalysts were prepared in the same manner asdescribed in Example I above except that the pH of the final wash waterwas varied. Separate slurries were formed with pH of from 8 to 12 andeach catalyst was then doped with a precious metal, as described below.

Standardized aqueous solutions of Pd salts and of Pt salts were formed.These solutions had a pH of about 9 to 10.

A series of doped catalyst were formed by introducing with agitation aportion of a standardized precious metal salt solution having a preciousmetal content of from 0.1 to 1.0 weight percent precious metal based onthe spongy nickel catalyst (solid content) of the treated slurry. Thetreated slurry was maintained under agitation for about 30 minutes. Theagitation was then stopped and the solids allowed to settle. A portionof the liquid was decanted and analyzed for precious metal content. Theanalysis showed no precious dopant metal present in the spent liquid.The slurry was washed by cyclical water/decantation to a final pH ofabout 9 and with at least 25 parts by weight of water for each part ofcatalyst product. The resultant precious metal doped spongy nickelcatalysts were stored under water for at least one day prior to beingtested and used.

Table I below provides the data and description with respect to each ofthe series of samples produced. This description includes:

precious metal dopant salt (PM)

dosage of dopant in the doped catalyst (% precious metal based on nickelof spongy catalyst)

pH of dopant solution

pH of catalyst slurry before doping treatment

pH of catalyst slurry after (post) doping treatment

bulk analysis (ICP) of doped catalyst

Surface Analysis (XPS) of doped catalyst

Surface to Bulk (S/B) Ratio

Bulk chemical analysis was analyzed by Inductive Coupled Plasma-AtomicEmission Spectroscopy (“ICP”). Each sample was washed with water andthen completely dissolved in a mixture of HCl/NHO₃ acid (3:1) solution.The sum of the percent assays determined was normalized to 100%. Theweight percentages for precious metal, nickel, and residual aluminum arereported in Table I as well as the atomic ratio of precious metal tonickel.

The average precious metal dopant concentration at the doped catalystparticles'outer shells (surface volume) was determined by X-rayPhotoelectron Spectroscopy (XPS). For each measurement, a small sampleof about 0.5 g water-wet catalyst was removed from its slurry and driedin a U-shaped tube under flowing helium gas at a temperature of 130° C.The dried sample is then sealed in the tube and transported to the XPSinstrument. The sample was introduced via an antechamber to the XPSinstrument. XPS measurements were carried out on a PHI 5600 ESCA system(φ Physical Electronic). The catalyst was handled under an Argonatmosphere within an environmentally controlled glove box. Moisturecontent was no higher than 0.40 ppm and oxygen content was generally0.00 ppm within the glove box environment.

Spectra were obtained using an aluminum x-ray source operating at 14.8kV/25 mA energy and the detector positioned at 45° relative to thematerial being analyzed. Instrument calibration was performed using a Cureference standard after 10 minutes sputtering in Argon. Because the2_(p3/2) and 3_(p3/2) photoelectron peak energies of Cu are widelyseparated in energy, measurement of these peak binding energies provideda quick and simple means of checking the accuracy of the binding energyscale.

The material was loaded as a thin layer onto double-sided tape mountedto a 1 inch diameter stainless steel stub. The stub was placed in anenclosed transfer vessel and mounted onto the intro chamber of the XPSinstrument. The sample was transferred in vacuo (10⁻⁶ torr) into themain analysis chamber and further vacuum of 10⁻⁸ to 10⁻⁹ torr wasachieved. A 5 minute surface scan to identify all detectable elementsfrom 1-1100 eV was performed. Based on the findings from the survey, a60 minute detailed scan on selected elements was performed with anenergy resolution of 0.125 eV. For convenience, the spectral data wereimported into an external curve-fitting software package (MULTIPAKv2.2a). Other conventional methods can be used. All the curve-fittingand atomic concentration functions were performed using this software.Sensitivity factors for each element were automatically configuredwithin the software and used in the atomic concentration calculations.

The Surface/Bulk (“S/B”) ratio was calculated as follows (e.g., with Pdand Ni as dopant and base metal, respectively):${{S/B}\quad {ratio}} = {\frac{{surface}\quad {{Pd}/{Ni}}}{{bulk}\quad {{Pd}/{Ni}}}\quad {which}\quad {is}}$$\frac{\left\lbrack \left( {{XPS}\quad {Pd}\quad {atom}\quad {{concentration}/\left( {{XPS}\quad {Ni}\quad {atom}\quad {concentration}} \right)}} \right\rbrack \right.}{\begin{matrix}\left\lbrack {\left( {{ICP}\quad {bulk}\quad \% \quad {{Pd}/{atomic}}\quad {wt}\quad {Pd}} \right)/} \right. \\\left. \left( {{ICP}\quad {bulk}\quad \% {\quad \quad}{{Ni}/{atomic}}{\quad \quad}{{wt}.\quad {Ni}}} \right) \right\rbrack\end{matrix}}$

EXAMPLE III

A sample was made in the same manner as described above in Example IIfor Samples 2D-2F except that the base metal catalyst was nickel basedhaving about 2 wt. % Fe and 2 wt. % Cr in the spongy catalyst.

The dopant catalyst was analyzed in the same manner as described aboveand the results are reported as Sample 3 in Table I below.

TABLE I Dopant (PM) Salt Bulk Analysis ICP Surface Vol. Target CatalystSlurry pH Atom PM/Ni Example Conc. Salt pH Pre-doping Post-doping % PM %Ni % Al PM/Ni (XPS) S/B Ratio 1 — None — — — — — — — — — 2A   ˜1%(NH₃)₄PdCl₂.H₂O 9.1 11 9.6 1.17 92.9 5.6 0.00695 0.17 24 2B  0.5%(NH₃)₄PdCl₂.H₂O 9.1 11 9.6 0.53 93.9 5.3 0.00311 0.10 32 2C  0.5%(NH₃)₄PdCl₂.H₂O 9.1 11 9.9 0.46 93.8 5.4 0.00270 — — 2D 0.25%(NH₃)₄PdCl₂.H₂O 9.1 11 9.7 0.25 94.0 5.5 0.00147 0.06 41 2E 0.25%(NH₃)₄PdCl₂.H₂O 9.1  8 9.0 0.26 94.3 5.1 0.00152 0.08 53 2F 0.25%(NH₃)₄PdCl₂.H₂O 9.1  9 8.9 0.28 93.8 5.7 0.00165 0.03 18 2G 0.25%(NH₃)₄PdCl₂.H₂O 9.1 10 9.0 0.25 93.8 5.7 0.00147 0.04 27 2H 0.25%(NH₃)₄PdCl₂.H₂O 9.1 11 10.3 0.22 92.9 6.6 0.00131 0.03 23 2I 0.25%(NH₃)₄PdCl₂.H₂O 9.1 12 12. 0.27 93.5 5.9 0.00159 0.05 31 2J 0.25%(NH₃)₄PtCl₂.H₂O 8.1 11 10.9 0.27 94.3 5.1 0.00158 — — 2K 0.125% (NH₃)₄PdCl₂.H₂O 9.1 11 10.8 0.14 93.6 6.0 0.00083 0.02 24 3 0.25%(NH₃)₄PdCl₂.H₂O 9.1 11 11.0 0.25 89.3 10.2 0.00155 0.08 52

EXAMPLE IV

A series of catalytic hydrogenation reactions to convert 4-nitrotolueneto 4-methyl aniline were carried out using Pd doped nickel basedcatalyst, as follows:

10 parts of a selected catalyst was transferred into a reaction flask,washed twice with 12000 parts of 95% ethanol/5% water (PharmcoProducts). Then 12000 parts of 95% ethanol containing 500 parts of4-nitrotoluene (Aldrich) was introduced into the reaction flask. Thereaction flask was evacuated and filled with hydrogen gas. Stirring ofthe solution at 1200 rpm was commenced when the temperature reached 75°C. and the pressure was at 60 psig. Each reaction was conducted induplicate.

The hydrogenation reaction was monitored using a multi-point absorptionreactor system which measured the gas uptake at constant reactionpressure. This was accomplished by measuring the pressure drop in apre-calibrated ballast reservoir. The system was capable of recordingthe parameters of reaction time, pressure, temperature and pressure inballast reservoir. These parameters were recorded at the rate of 12points/minute during the first 10 minutes of reaction and then atincrements of each 1 percent pressure drop in the ballast reservoir. Thedata obtained were plotted versus time and the reaction rates werecalculated from the slope in the linear portion of the hydrogen uptake.At the completion of each reaction, aliquots of reaction solution weretaken and analyzed by gas chromatography-mass spectrometry. The only twomaterials identified were the starting 4-nitrotoluene and the4-methylaniline product.

The results are given in Table II below.

TABLE II Catalyst Activity 4-nitrotoluene conversion at 75° C./60 psigBase Catalyst Cat. Activity rate Sample Pd* wt. % predoped pH mmolH₂/min-g catalyst 2E 0.25 8 57 2F 0.25 9 77 2G 0.25 10 77 2H 0.25 11 852I 0.25 12 62 2J 0.50 11 73 2K 0.125 11 66 *source of Pd was(NH₃)₄PdCl₂.H₂O

EXAMPLE V

A series of hydrogenation reactions of 4-nitrotoluene was conductedusing different combinations of temperature and pressure conditions (amatrix of Temp/Pressure combinations using 200 and 400 psig and 125° C.and 140° C.). The catalyst used was palladium doped nickel basedcatalyst (2G) described in Example II above.

Each of the hydrogenation reactions were conducted using a Bench Top EZESeal Reactor (Autoclave Engineers) which is divided into a feed section,a high pressure section and a low pressure section. The reactor was alsoequipped with the pressure drop sensing monitor described in Example IVabove. The reactor feed section is equipped with lines for hydrogen,nitrogen and vacuum. The high pressure section of the reactor has aforward pressure regulator, a varying volume ballast reservoir and apressure transducer. The low pressure section is in-line with thereactor and its pressure was monitored by a pressure transducer.

During each reaction, the gas consumption in the reactor section causeda continuous pressure drop in the calibrated ballast reservoirs. Thepressure of the ballast, the autoclave pressure, the tachometer reading,the hydrogen consumption and the reaction temperature were continuouslymonitored and recorded as described in Example IV.

In each reaction, 65 parts of wet catalyst (2G) was transferred into thereactor beaker, washed with 12000 parts 95% ethanol/5% water (PharmcoProducts) and then the reactor was sealed, and connected to EZE reactor.The system was evacuated and filled with hydrogen followed by theaddition of 28000 parts of an ethanol solution which contains 3500 partsof 4-nitrotoluene via a gas-tight syringe. The reactor was pressurizedwith hydrogen to the indicated pressure (either 200 or 400 psig) andthen heated to the indicated temperature (either 125° C. or 140° C.).When the temperature/pressure parameters were reached, stirring (1300rpm) and data acquisition was simultaneously initiated. After gasabsorption ceased the reactor was cooled and the liquid phase extractedunder pressure. Each set of reaction conditions was used in duplicateruns. Table III below provides the initial catalyst activity in terms ofconversion of 4-nitrotoluene (mmol H₂/min) for each of the fourconditions of the temperature/pressure matrix.

TABLE III Initial Catalyst Activity (Sample 2G) (mmol H₂/min) ReactionTemperature H₂ Pressure psig 125° C. 140° C. 200 45 3.4 400 49 9.6

The above results show that increases in either temperature or pressurealone do not enhance the catalytic activity of the present catalyst(similar results are achieved with acid salt doped catalyst). However,the subject catalyst shows synergistic high catalyst activity underincreased combined temperature/pressure conditions.

EXAMPLE VI

A series of catalyst were tested for their response to recyclingreactions (each used in five consecutive (5) batch reactions). Theseries included catalyst 2G and, for comparative purposes. Catalystsformed according to examples I (Sample I) and Comparative Example II(Sample 5F) (see below). The reactions were each carried out using theprocedure and reactor equipment described in Example VIII undertemperature/pressure combined conditions of 140° C. and 400 psig. At theend of the fifth cycle, the substrate (4-nitroluene) to catalyst contactratio reached a total of 250.

The results are shown in Table IV below. The precious transition metaldoped catalyst of the present invention exhibited superior activity overthe cycles tested when compared to undoped catalyst (Sample 1) and toconventional acid salt doped catalyst (Sample 5F).

TABLE IV Catalyst Activity in Batch Recycle Activity mmol H₂/min CycleSample 2G Sample 5F Sample 1 1 9.6 7.4 5.5 2 8.9 5.0 3.9 3 5.0 2.9 2.6 43.7 3.1 2.3 5 3.2 3.2 2.2

The above shows that undoped base metal catalyst had lower catalyticactivity in each of the five cycles than doped catalyst. However, of thedoped catalysts, the present doped catalyst exhibited higher initial andoverall activity than conventional acid salt doped catalyst.

COMPARATIVE EXAMPLE I

For comparative purposes, a sample of base metal catalyst was preparedin the same manner as in Example II above except that the dopant saltsolution was formed with a solution of palladium salt (NH₃)₄Pd(OH)₂—H₂O,having a pH of 13.7. The resultant doped catalyst is labeled1-Comparative. This high pH dopant solution was used to prepare a dopedcatalyst formed with the same nickel base catalyst of samples 2D (havinga pre-dopant pH of 11) and the same concentration (0.25 wt. percent) ofPd metal dopant of those samples. The results are shown in Table I-Cbelow and compared with those of samples 2D.

TABLE I-C Catalyst Slurry pH PM/Ni (atomic) Dopant Pre- Post- SampleSol. pH Doping Doping. ICP XPS S/B 2D 9.1 11 9.7 0.00147 0.06 411-Comparative 13.7 11 11.9 0.0013 0.15 116

COMPARATIVE EXAMPLE II

For comparative purposes, a series of palladium metal doped nickel basemetal catalysts were formed using the same procedure described inExample II above except that acidic precious metal salt solutions wereused to provide the dopant metal. The samples were analyzed in the samemanner as described in Example II using ICP and XPS techniques. Theresults are given in Table II-C. The resultant doped catalyst productshad very high S/B ratio showing that a much greater fraction of thedoped metal resided in the surface volume of the catalyst particles.

TABLE II-C Dopant (PM) Salt Bulk Analysis ICP Surface Vol TargetCatalyst Slurry pH Atom PM/Ni (atomic) Sample Conc. Salt pH Pre-dopingPost-doping % PM % Ni % Al PM/Ni (XPS) S/B Ratio 5A   1% PdCl₂ −0.2 96.7 0.92 93.8 5.0 0.00541 0.63 116 5B  0.5% PdCl₂ −0.2 11 7.6 0.51 92.36.9 0.00305 0.27  89 5C 0.25% Na₂Pd(II)Cl₄ 4.0 11 10.2 0.29 93.8 5.60.00171 0.17 100 5D 0.25% Na₂Pd(IV)Cl₆ 2.0 11 10.2 0.28 93.5 5.9 0.001650.25 151 5E 0.25% Pd(NO₃)₂ −0.7 11 11.1 0.28 93.7 5.7 0.00165 0.17 1035F 0.25% PdCl₂ −0.2 8.7 8.0 0.25 92.9 6.6 0.00149 0.18 121 5G 0.25%PdCl₂ −0.2 9.0 8.1 0.26 93.9 5.5 0.00153 0.25 164 5H 0.25% PdCl₂ −0.2 107.3 0.25 93.9 5.6 0.00147 0.17 116 5I 0.25% PdCl₂ −0.2 11 9.2 0.27 93.36.1 0.00160 0.13  81 5J 0.25% PdCl₂ −0.2 12 12.6 0.25 94.4 5.1 0.001460.13  89 5K 0.125%  PdCl₂ −0.2 11 8.0 0.124 95.0 4.6 0.00072 0.08 111

The data in Tables I-C and II-C shows a strong dependency of the S/Bratio on the type of salt used and the, thus pH of the dopant solutionwhich provides the dopant precious metal. The high S/B ratio attainedwhen an acidic dopant salt or a very alkaline dopant salt (Sample1-Comparative) is used indicated that one does not achieve the same typeof dopant distribution as when using dopant salts having a pH in therange of from about 8-12.

COMPARATIVE EXAMPLE III

For comparative purposes, a series of Pd acid salt formed catalysts,Samples 5G to 5J were tested in the same manner as above and compared toSamples 2H, 2I, 2F, and 2K in Table III-C below. Each compared pair ofsamples contained 0.25 wt. % Pd dopant and were formed using spongynickel metal catalyst slurries having the same pre-doping pH condition.

TABLE III-C Ni catalyst pre-doped pH Salt 9 10 11 12 NH3PdCl2.H2O 77 7785 62 PdCl₂ 61 74 68 61

The present basic salt formed doped catalyst provided a higher activityin each comparison.

COMPARATIVE EXAMPLE IV

For comparative purposes, duplicate hydrogenation reactions of4-nitrotoluene were conducted in the same manner as described in ExampleV at reaction conditions of 140° C. and 400 psig except that thepalladium doped nickel based catalyst used was Sample 2G prior towashing and aging. The catalytic activity was only 7.4 mmol H₂/mincompared to the 9.6 mmol H₂/min value obtained under the same conditionswith the catalyst of the present invention.

What is claimed is:
 1. A product comprising a porous particulate metalmaterial comprising a porous sponge base metal alloy having a majoramount of a metal selected from Ni, Co, Cu, Fe or mixtures thereof, andhavinq from about 0.01 to about 1.5 weight percent of a precioustransition metal coated on the surface of said base metal alloy anddistributed throughout said particulate material to have a S/B ratio ofless than
 60. 2. The product of claim 1 wherein the precious transitionmetal is selected from Ru, Rh, Re, Pd, Pt, Os, Ir or mixtures thereof.3. The product of claim 2 wherein the precious transition metal isselected from Pt or Pd or mixtures thereof and the base metal isselected from nickel, cobalt or mixtures thereof.
 4. The product ofclaim 3 wherein the precious transition metal is present in from 0.05 to1 weight percent and the S/B ratio is from about 10 to
 50. 5. Theproduct of claim 3 wherein the porous particulate base metal materialhas an average particle diameter of less than 500 microns and a surfacearea of at least 10 m²/g.
 6. The product of claim 5 wherein the porousparticulate base metal material has an average particle diameter of lessthan 75 microns and a surface area of at least 10 m²/g.
 7. The productof claim 2 wherein the S/B ratio is from about 10 to about
 40. 8. Theproduct of claim 2 wherein the precious transition metal is present infrom 0.05 to 1 weight percent and the S/B ratio is from about 10 to 50.9. The product of claim 2 wherein the porous particulate base metalmaterial has an average particle diameter of less than 500 microns and asurface area of at least 10 m²/g.
 10. The product of claim 9 wherein theporous particulate base metal material has an average particle diameterof less than 75 microns and a surface area of at least 10 m²/g.
 11. Theproduct of claim 2 wherein the porous particulate base metal materialhas a particle diameter range of from 0.1 to 0.8 cm and a surface areaof at least 10 m²/g.
 12. The product of claim 1 wherein the S/B ratio isfrom about 10 to about
 40. 13. The product of claim 2 wherein the porousparticulate base metal material has a surface area of from 20 to 150m²/gm; the promoter precious metal is selected from Pt or Pd or mixturesthereof; the amount of promoter precious metal in the product is from0.05 to 1 weight percent; and the S/B ratio is from about 10 to
 40. 14.The product of claim 1 wherein the sponge porous base metal alloycomprises at least 85 weight percent of a base metal selected from Ni,Co, Cu, or Fe or mixtures thereof and further comprises up to 15 weightpercent of aluminum, molybdenum, chromium, iron, copper, tin, zirconium,zinc, titanium, vanadium or mixtures thereof.
 15. The product of claim14 wherein the precious transition metal is present in from 0.05 to 1weight percent and the S/B ratio is from about 10 to
 50. 16. The productof claim 14 wherein the porous particulate base metal material has asurface area of from 20 to 150 m²/gm; the promoter precious metal isselected from Pt or Pd or mixtures thereof; the amount of promoter metalin the product is from 0.05 to 1 weight percent; and the S/B ratio isfrom about 10 to
 40. 17. The product of claim 14 herein the porousparticulate base metal material has an average particle diameter of lessthan 500 microns and a surface area of at least 10 m²/g.
 18. The productof claim 1 wherein the porous particulate metal material further has upto about 3 weight percent of a metal selected from the group consistingof molybdenum, chromium, zirconium, zinc, titanium, vanadium, iron ormixtures thereof on the surface of said base metal material.
 19. Theproduct of claim 18 wherein the precious transition metal is present infrom 0.05 to 1 weight percent and the S/B ratio is from about 10 to 50.20. The product of claim 18 wherein the porous particulate base metalmaterial has a surface area of from 20 to 150 m²/gm; the promoterprecious metal is selected from Pt or Pd or mixtures thereof; the amountof promoter precious metal in the product is from 0.05 to 1 weightpercent; and the S/B ratio is from about 10 to
 40. 21. The product ofclaim 1 wherein the porous particulate base metal material has aparticle diameter range of from 0.1 to 0.8 cm and a surface area of atleast 10 m₂/g.
 22. The product of claim 1 wherein the porous particulatebase metal material has a surface area of from 20 to 150 m²/gm; thepromoter precious metal is selected from Pt or Pd or mixtures thereof;the amount of promoter precious metal in the product is from 0.05 to 1weight percent; and the S/B ratio is from about 10 to
 40. 23. A productcomprising a porous particulate metal material comprising a spongeporous base metal alloy having at least about 85 weight percent of abase metal selected from Ni, Co, Cu or Fe or mixtures thereof andfurther comprising up to 15 weight percent of aluminum, molybdenum,chromium, iron, copper, tin, zirconium, zinc, titanium, vanadium ormixtures thereof, and further having from about 0.01 to about 1.5 weightpercent of a precious transition metal coated on the surface of saidbase metal and distributed throughout said porous particulate materialto have a S/B ratio of less than
 60. 24. The product of claim 23 whereinthe precious transition metal is selected from Ru, Rh, Re, Pd, Pt, Os,Ir or mixtures thereof.
 25. The product of claim 23 wherein the precioustransition metal is selected from Pt or Pd or mixtures thereof and thebase metal is selected from nickel, cobalt or mixtures thereof.
 26. Theproduct of claim 25 wherein the precious transition metal is present infrom 0.05 to 1 weight percent and the S/B ratio is from about 10 to 50.27. The product of claim 26 wherein the porous particulate metalmaterial has an average particle diameter of less than 500 microns and asurface area of at least 10 m²/g.
 28. The product of claim 25 whereinthe porous particulate metal material has an average particle diameterof less than 500 microns and a surface area of at least 10 m²/g.
 29. Theproduct of claim 24 wherein the precious transition metal is present infrom 0.05 to 1 weight percent and the S/B ratio is from about 10 to 50.30. The product of claim 29 wherein the porous particulate metalmaterial has an average particle diameter of less than 500 microns and asurface area of at least 10 m²/g.
 31. The product of claim 24 whereinthe porous particulate metal material has an average particle diameterof less than 500 microns and a surface area of at least 10 m²/g.
 32. Theproduct of claim 23 wherein the porous particulate metal materialfurther has up to about 3 weight percent of a metal selected from thegroup consisting of molybdenum, chromium, zirconium, zinc, titanium,vanadium, iron or mixtures thereof on the surface of said base metalmaterial.
 33. The product of claim 32 wherein the precious transitionmetal is present in from 0.05 to 1 weight percent and the S/B ratio isfrom about 10 to
 50. 34. The product of claim 33 wherein the porousparticulate metal material has an average particle diameter of less than500 microns and a surface area of at least 10 m²/g.
 35. The product ofclaim 32 wherein the porous particulate metal material has an averageparticle diameter of less than 500 microns and a surface area of atleast 10 m²/g.
 36. The product of claim 23 wherein the precioustransition metal is present in from 0.05 to 1 weight percent and the S/Bratio is from about 10 to
 50. 37. The product of claim 36 wherein theporous particulate metal material has an average particle diameter ofless than 500 microns and a surface area of at least 10 m²/g.
 38. Theproduct of claim 23 wherein the porous particulate metal material has anaverage particle diameter of less than 500 microns and a surface area ofat least 10 m²/g.
 39. The product of claim 5, 6, 9, 10, 11, 17, 21, 27,28, 30, 31, 34, 35, 37 or 38 wherein the S/B ratio is from about 10 toabout 50.